There are two overall objectives for this grant. The first is to obtain data on how hyperthermia kills cells, and the second is to develop information of specific views for clinical hyperthermia treatment. The specific aims of the basic studies are: (1) mapping of membranes of heated and/or thermotolerant cells, (2) use of temperature-sensitive mutants to study the mechanism of thermotolerance, (3) determine the effects of glucose, oxygen concentration, pH, on ATP intracellular levels, and on heat-sensitivity, and (4) to measure intracellular pH as a function of extracellular pH. Our clinically-oriented studies will examine (1) the decay of thermotolerance both in vitro and in vivo, (2) quantification of heat damage of various pig tissues, examining the possibility of their protection by thermotolerance, (3) the effects of development of thermotolerance on X-ray and drug sensitivity in vitro and in vivo, and finally (4) the optimum number of heat treatments to be associated with a course of fractionated X-ray therapy. Techniques to be utilized include P31 NMR, ESR, competitive finding studies of lectins, hormones and antigens. The data should provide information regarding the advantageous use of hyperthermia against localized malignant lesions.